You lose all the items you have, including cash, armor, ships, etc. that you purchased in-game.
They are going to try and not wipe your reputations.
The only items you will keep is the stuff you bought with real money or were credited to your account via rewards or subscription flair.
I've been seeing a lot of complaints on that thread. "But I just spent 4 months grinding for my hammerhead"... etc.
I know this is an alpha, but a lot of people seem to think of this as a released game, and CIG waffles back and forth in their communication. Yes, a lot of it does say "this is an alpha", some of their verbal communications indicate otherwise "this is a live service". CIG needs to stop trying to get people to jump in thinking it's a finished game and actually give a consistent "this is alpha" statement.